(i) Field of the Invention
The present invention relates to a quinophthalone compound which is useful as a coloring agent for liquid crystal materials and organic polymeric materials.
(ii) Description of the Prior Art
Heretofore, it has been known that liquid crystal materials and organic polymeric materials are colored by using quinophthalone derivatives represented by the formula ##STR1## wherein R is an alkoxy group, alkylamino group or aralkyloxy group, and n is an integer of from 1 to 8, as dyestuffs (e.g., Japanese Patent Publication No. 20476/1973, and Japanese Patent Laid-open Nos. 93778/1983, 4674/1984, 4675/1984, 182877/1984 and 182878/1984).
However, when used to color the liquid crystal materials and organic polymeric materials, these compounds are unusable on occasion, because they are insufficiently compatible with a liquid crystal compound, a solvent, a binder matrix and the like. For example, when the compatibility of the quinophthalone compound with the liquid crystal compound is low, the contrast required for a guest-host type liquid crystal composition cannot be obtained. Furthermore, when the solubility of the quinophthalone compound in the solvent is low, a dyestuff-organic polymer coating film formed by a solvent coating method cannot possess a sufficient optical density. When the compatibility of the quinophthalone compound with the binder matrix is low, a polymeric film cannot be dyed at a high concentration, and the film in which the known quinophthalone compound is dispersed at a high concentration is opaque and cannot be used as a color filter or the like where transparency is required.